The Lockey Systems EDigSN E-Digital Electronic Deadbolt Lock is an electronic lock with 6 available user codes, one-time user code, illuminated key pad, auto-stop function, and audible and visual confirmations. Change user codes in seconds. Temporarily disable user codes when not needed or delete them individually or all at once. One-time user code allows access for repair or temporary personnel so they can only enter one time. Four AAA Alkaline Batteries (sold separately) last up to 1 year with normal operation. Battery power means there is no messy wiring required so the Deadbolt is easy to install. Indicator shows when batteries are getting low.